Nowadays I think pretty much every webmaster and web site owner knows that if you can get more quality backlinks to your web site, it can help you improve your rankings in search engines (especially Google). The higher your rank in search engines, that is to say the nearer the top of the search results you are for searches on relevant keywords, the more traffic that your web site will get. And, the more traffic that your web site gets, the more money you can make, whether it is from selling your own products and services, from commissions on sales of affiliate products, or from advertising programs such as Google AdSense.
One obvious way to get links to your site is to exchange links with other sites. As much as anything is, this might be considered a traditional form of web site promotion. Exchanging links is however time consuming, since you need to spend time finding sites to swap links with, and you must then set up the links and monitor them on an ongoing basis. Another disadvantage of each exchanging links, is of course that you are not just links coming into your site, you also linking to, and sending traffic to, other sites.
If you want other sites to link to you, without having to link back, there are several options:
1. You may be able to find some directories that accept free submissions. Of course, the number of good quality directories that accept free submissions is usually quite limited - as too many free submissions will tend to result in a good quality directory quickly turning to junk.
2. You may be able to pay other sites to link to you. Of course this can cost quite a bit of money, and you may also find that search engines take a dim view of such activity - perhaps penalizing or evening banning your site from their listings!
3. You can provide interesting content on your site (known as "link bait") and simply hope that people choose to link to it. Of course, you may get lucky, but this approach is hit and miss to put it mildly.
4. You can write articles and submit them to article directories. This is actually the best option, since writing a few hundred words about a topic which relates to your business and which you already know something about, is not too difficult. When you submit your article to a directory, you will be allowed to include a "resource box" or "bio" section, which may contain a backlink to your own web site. Additionally, since there are hundreds of article directories, even writing a single article can result in hundreds of backlinks. Of course, the difficulty is that submitting to hundreds of directories can take a lot of effort if done manually - so I'd suggest you invest in some article submitter software, and automate the process. Don't expect massive results from just one article, but if you make writing and submitting articles a regular activity, over time, it can lead to some impressive results.